Figure 6.

The binding sites of trans-crotglycine (tcg) and cis-crotglycine (ccg) in met/MetRS(FF), predicted in the “activation mode” as described in Materials and Methods. ccg (orange) has van der Waals clashes with Ala 12, His 301, and Tyr 260 and at the same time, the cis orientation of the terminal methyl group created a void near Ala 256 and Pro 257. tcg (pink), the trans form of the methyl group, fills the void near Ala 256 and Pro 257. tcg does not have unfavorable van der Waals interactions.